Method, System and Apparatus for Interbody Fusion

ABSTRACT

Methods, systems and apparatus are provided for interbody fusion. In some embodiments, a device is provided for fusing vertebral bodies. The device includes a shell configured to be disposed between a first body and a second body, an injection opening to receive fusing material, and a delivery hole configured to enable fusing material to flow into at least one of the first body and the second body.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/654,345, filed Jan. 16, 2007 and titled “Method, System andApparatus for Interbody Fusion,” which is a continuation of U.S. patentapplication Ser. No. 11/031,511, filed Jan. 7, 2005 and titled “Method,System and Apparatus for Interbody Fusion,” which claims priority toU.S. Provisional Patent Application No. 60/535,227, filed Jan. 9, 2004and titled “Method, System and Instrumentation for Interbody Fusion,”the entire contents of each are incorporated herein by reference.

FIELD

The present disclosure relates generally to methods, systems, andapparatus for interbody fusion, and more particularly, to methods,systems, and apparatus for interbody fusion of one or more adjacentvertebral bodies.

BACKGROUND

Back and neck pain may cause disability and discomfort which may affectan individual's lifestyle. There are various levels of back and neckpain, from a low-level annoyance to extreme discomfort and debilitatingpain. Depending on the type of pain and the cause of the pain, multipleoptions may be available to reduce and/or treat back and neck pain.Where conservative non-invasive techniques are inadequate, surgicaltreatment options may be available to reduce or eliminate such backand/or neck pain. For example, surgical treatment options may be used todecompress a nerve root, stabilize a lumbar or cervical joint, reduce adeformity of the spine, etc.

The degeneration, rupture or herniation of the intervertebral discs ofthe spine may cause back or neck pain. One exemplary type of lower backpain is due to degeneration of lumbar discs in the spine. Surgicaloptions, such as lumbar fusion, may be available to relieve such lowerback pain.

Two common types of lumbar fusion are postlateral fusion (PLF) andinterbody fusion, including anterior lumbar interbody fusion (ALIF) andposterior lumbar interbody fusion (PLIF). In the lumbar fusion methods,described briefly below, a metal construct is often used to temporallystabilize the motion segment while awaiting development of a rigidosseous construct.

PLF may include positioning a bone graft external to the ruptured discsuch that adjacent spinal bones (spinal segments) grow together. Screwsand plates, such as pedicle screws, may be used to stabilize and preventmotion of adjacent spinal bones as they fuse together. Because PLF isnot an interbody fusion, the surgery may be easier. However, PLF may notrelieve back pain in some situations because the damaged disc remainsintact within the spine and may continue to cause discomfort.

Each of the interbody fusions includes inserting a bone graft or similarobject directly into the disc space. ALIF is an interbody fusion wherethe incision is through the front side of the body, such as through theabdomen. Typically, a three to five inch incision may be made on theabdomen. Through this incision, one or more lumbar discs may be removed.The discs may be replaced with a bone graft and/or a fusion cage.Because the large blood vessels to the lower extremities lay on top ofthe spine, the skill of a vascular surgeon may be needed to gain accessto the spine. Moreover, there may be an increase in the risk ofcomplications, such as hemorrhage, due to the close proximity of thelarge blood vessels to the spine. The risk of other complications,including unintentional sympathectomy and retrograde ejaculation inmales, may also increase.

PLIF is an interbody fusion where entry is through the backside of thebody. Typically, a three to six inch long incision in the midline of theback may be cut to obtain access to the spine. Due to the backsideentry, substantial retraction of the nerve roots is necessary to gainaccess to the disc space. PLIF may further require extensive boneremoval to access the disc space, which may increase the possibility ofposterior migration of a fusion cage. Furthermore, the backside entryoften damages the muscle tissue surrounding the disc space and adjacentspinal bones. The damage to the surrounding muscles complicates andprolongs the recovery process. Additionally, there may be an increasedrisk in extensive blood loss due to the epidural veins over the discspace.

For both ALIF and PLIF, the quality of the adjacent spinal bones mayaffect the quality and success of the fusion. For example, conditionscharacterized with poor bone quality, such as osteopenia andosteoporosis, may significantly decrease fusion rates. As describedabove, the conventional fusion methods may result in complications, suchas neurological, dural, osteal, and muscular complications. Moreover, inmany situations, these procedures require long hospital stays.

SUMMARY

Methods, systems and apparatus are provided for interbody fusion. Insome embodiments, a device is provided for fusing vertebral bodies. Thedevice may include a shell configured to be disposed between a firstbody and a second body, an injection opening to receive fusing material,and a delivery hole configured to enable fusing material to flow into atleast one of the first body and the second body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified lateral view of the lumbar region of the spinalcolumn.

FIG. 2 is a simplified axial view of a lumbar vertebral body and a disc.

FIG. 3 is a block diagram of a method for augmented micro lumbarinterbody fusion (AMLIF) according to an embodiment of the presentdisclosure.

FIG. 4 is a simplified side view of a delivery device disposed in a discspace with a material restrictor being funneled into the disc spaceaccording to an embodiment of the present disclosure.

FIG. 5 is a simplified side view of an alternative embodiment of thedelivery device being disposed in a disc space with a materialrestrictor being funneled into the disc space according to analternative embodiment of the present disclosure.

FIG. 6 is a schematic illustration of a delivery device and a materialrestrictor according to an embodiment of the present disclosure.

FIG. 7 is a side view of a delivery device and a material restrictordisposed in a disc space.

FIG. 8 is a perspective view of a material restrictor according to anembodiment of the present disclosure.

FIG. 8 a is a schematic illustration of another material restrictoraccording to an embodiment of the present disclosure.

FIG. 9 is a simplified illustration of the use of a drill to create adelivery channel into a vertebral body according to an embodiment of thepresent disclosure.

FIG. 10 is a simplified illustration of a disc space prepared for fusionaccording an embodiment of the present invention.

FIG. 11 is a simplified illustration of a fusing material beingdelivered to the vertebral bodies according to an embodiment of thepresent disclosure.

FIG. 12 is a simplified illustration of a completed AMLIF with fusingmaterial extending between the vertebral bodies and a materialrestrictor according to an embodiment of the present disclosure.

FIGS. 13 and 13 a are schematic illustrations of another embodiment of amaterial restrictor according to an embodiment of the presentdisclosure.

FIGS. 14, 14 a and 14 b are additional illustrations of a materialrestrictor including distribution channels according to an embodiment ofthe present disclosure.

FIGS. 15 and 15 a are schematic illustrations of a delivery deviceaccording to an embodiment of the present disclosure.

FIGS. 16 and 16 a are further illustrations of the delivery device ofFIGS. 15 and 15 a and a material restrictor showing operative attachmentof the delivery device to the material restrictor according to anembodiment of the present disclosure.

FIG. 17 a illustrates a first operation of a delivery device forinsertion of a restrictor into a disc space according to an embodimentof the present disclosure.

FIGS. 18 a and 18 b illustrate insertion of fusing material through adelivery device into a restrictor according to an embodiment of thepresent disclosure.

FIGS. 19 a and 19 b illustrate drilling of delivery channels intoadjacent vertebral bodies according to an embodiment of the presentdisclosure.

FIG. 20 illustrates delivery of fusing material into adjacent vertebralbodies according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates generally a simplified lateral view of the lumbarregion of the spinal column 10. Spinal column 10 includes a plurality ofseparate bones or vertebral bodies 12 a-12 e. Interposed the vertebralbodies 12 are intervertebral discs 14 a-14 d. The intervertebral discsmay function as both ligaments and as shock absorbers. Damage to, orrupture of, these discs may be treated by fusing two or more of thevertebrae together.

Although the present disclosure describes fusing one or more vertebralbodies in the lumbar region, it should be appreciated that similarmethods, systems, and apparatus/devices may be used to fuse bones ofother regions of the spinal cord or elsewhere in the body. For example,the methods, systems, and/or apparatus may be used to fuse the cervicalregion of the spine, the thoracic region of the spine, or other regionsof the body with adjacent bones that may be fused together. Moreover,such disclosure is described in regards to fusing human bones together,however, it is possible that the disclosed methods, systems, andapparatus may be used in veterinary practice.

For ease of reference and to better understand the present disclosure,FIG. 2 illustrates schematically, at 20, an axial view of a typicalintervertebral disc. Disc 20 includes a nucleus pulposus 22, which is agel-like region in the center of the disc. Nucleus pulposus 22 issurrounded by the annulus fibrosus 24. Attached to the outer portion ofannulus fibrosus 24, adjacent thecal sac 26, is posterior longitudinalligament (PLL) 28. Thecal sac 26 is disposed between PLL 28 and lamina30 and facets 32 of the spine. Thecal sac 28 may be an entry point forspinal nerves 34 and may wrap or surround other neural material.

In one embodiment of the present disclosure, as shown in block diagramformat in FIG. 3, a minimally-invasive method 40 (referred to herein asaugmented micro lumbar interbody fusion (AMLIF)) is provided for fusingtwo or more vertebral bodies. Method 40 is a minimally-invasive methodthat addresses the difficulties surrounding current fusion techniques,such as PLF, PLIF, ALIF. AMLIF may simplify lumbar fusions by providinga minimally invasive approach that may decrease morbidity and the lengthof post-operative hospital stays, while keeping the arthrodesis ratehigh. For example, in some embodiments, the AMLIF may be so minimallyinvasive to allow for same day surgery.

Moreover, the AMLIF procedure may expand patient selection criteria. Forexample, the AMLIF procedure may be used on soft poor quality bone (asseen with osteoporosis), thus providing additional options for suchpatients. In some embodiments, AMLIF further may be used with patientswith lumbar disc herniation, and other like conditions, to decrease therisk of recurrent disc herniation and progressive degenerativespondylosis.

Additionally, the AMLIF procedure may be practiced by spine surgeons,using known skills, without requiring additional specialization. Thus,most neurosurgeons and orthopedic spine surgeons will be able to use theAMLIF technique with low risk.

As described in more detail below, AMLIF further may provide a methodfor distraction to aid in foraminal decompression, reestablishing discspace height and maintaining normal lordotic curvature. In someembodiments, the AMLIF method and the associated hardware may functionto reduce and/or avoid subsidence, hardware migration, and hardwarefailure, thus, providing solid long-term segmental fusion.

Referring specifically to FIG. 3, AMLIF may include exposure of a disc,as indicated at 42. Several different methods may be used to expose thedisc. Typically, such methods may include making an incision through theepidermis and the dermis followed by incising, retracting, or removingmuscles, nerves, and bones to reveal the disc in the intervertebralspace.

For example, exposure of the disc, at 42, may be achieved through asmall incision. The incision may be a small 2-3 cm midline incision. Theincision may be smaller or larger, such as between about 0.5 cm andabout 5 cm, for endoscopic placement or when more than one disc is to beremoved. This small incision is in contrast to conventionalposterolateral fusions that typically require large incisions, on theorder of three to six inches.

The small midline incision of the present disclosure also may be usedfor endoscopic placement. Similar to the small midline incision throughthe epidermis and the dermis, a small incision, e.g. less thanapproximately 5 cm, may be made through muscle tissue that may bedisposed between the disc space and the initial incision. The petiteincision may help to preserve posterior stabilizing structures.

Following incision, and similar to a micro lumbar discectomy, bilateralpartial hemilaminotomies may be completed to expose the disc space.Additionally, neural material, such as the thecal sac and nerve roots,may require gentle retraction to provide access to the exposed discspace. The neural material may also be retracted during other steps ofthe method to provide access to the disc space. Although the disc isexposed for the purpose of interbody fusion, other pathology, such asherniated disc material, lateral recess stenosis, spinal stenosis, etc.,may be dealt with as desired once the disc is exposed.

Following exposure of the disc, the posterior longitudinal ligament andannulus may be incised and the disc may be removed (as indicated at 44).It should be understood that it may not be desirable or necessary toremove the entire disc, but that at least a portion of the disc materialmay be removed to open a disc space. Removal of the disc material may beaccomplished using any suitable method to open the disc space.

After removal of the disc, a delivery device may be inserted into thedisc space, at 46. The delivery device (described in more detail below)may be adapted to deliver a material restrictor or cage (referred toalso as a fusion restrictor and described in more detail below) into thedisc space. In some embodiments, the delivery device may includestructure to enable insertion of the material restrictor. In otherembodiments, the delivery device may include a selectively detachableportion which may function as the material restrictor. Moreover, in someembodiments, the delivery device may have multiple purposes, includingaiding in opening the disc space, aiding in drilling delivery channels,and or aiding in delivering fusing material into the materialrestrictor. The delivery device and the size of the material restrictormay simplify the fusion procedure and may be a minimally-invasive tissuedestruction approach.

As briefly described above, a material restrictor or interbody space orstabilizer may be selectively positioned in the disc space, as indicatedat 48 in FIG. 3. For example, in some embodiments, during or followingpositioning of delivery device 60, the material restrictor or cementrestrictor may be inserted into the disc space using delivery device 60,at 48. In one embodiment of the method, material restrictor 70 isimpacted down (tapped down) through delivery device 60 from the proximalend of the delivery device to the distal end of the delivery device.

Delivery device may include a guide configured to be at least partiallydisposed in the disc space and configured to funnel or guide thematerial restrictor into a select position within the disc space. Theguide may be any suitable device. For example, in one embodiment, theguide may include projections or tangs adapted to be at least partiallypositioned within the disc space. The projections or tangs may beelongated slides which enable positioning of a restrictor into the discspace. As described in more detail below, the tangs may includealignment features which may be used to guide positioning of therestrictor into the disc space. A portion of the tangs may be sized tocorrespond to the opened disc space.

As the restrictor is impacted through the delivery device, in someembodiments, the force may separate the tangs (or similar structure) ofthe delivery device distracting the disc space. Thus, impacting therestrictor into the disc space may function to reestablish normalanatomic disc space and decompress the adjacent neural foramina. Thedelivery device may be guided into position by structures or features onthe delivery device, on the material restrictor, or on both the deliverydevice and the material restrictor.

As briefly described above, the delivery device may function as aretractor to temporarily retract neural material such as a nerve rootand/or a thecal sac. Additionally, the delivery device may be configuredto act as a distractor to spread adjacent vertebral bodies that may beat least partially collapsed after removal of the disc material. In someembodiments, the delivery device may be configured with a proximal endoperable by a practitioner, such as a physician or surgeon performingthe procedure and with a distal end configured to be disposed in thedisc space. The practitioner may use the delivery device to open thedisc space to a select size to accommodate the material restrictor andreestablish normal anatomic disc space height.

The material restrictor may be inserted through the delivery deviceuntil it reaches a predetermined or select position within the deliverydevice. For example, in some embodiments, the select position in thedelivery device to which the material restrictor is inserted may bedisposed adjacent the distal end of the delivery device. In oneembodiment, the restrictor may be positioned substantially intermediatethe adjacent vertebral bodies.

As described in more detail below, the delivery device may include oneor more structures to aid in insertion, removal and placement of thedelivery device. For example, the delivery device may be configured withone or more stops configured to rest against the posterior surfaces ofthe vertebral bodies when the delivery device is fully inserted.

Although any suitable delivery device may be used in the method of thepresent disclosure, one exemplary delivery device 60 includes twodelivery tangs configured to be positioned into the disc space as shownin FIG. 4. As can be seen in the figure, first and second elongate tangs62, 64 may include cooperating first and second proximal ends 66, 68,respectively, configured to receive a material restrictor 70. First andsecond elongate tangs 62, 64 also may include cooperating first andsecond distal ends 72, 74 configured to be at least partially insertedinto disc space 14. As described above, disc space 14 may be at leastpartially collapsed due to the removal of the disc material in the priorstep. The delivery device 60 may be configured to allow the materialrestrictor 70 to be inserted from the proximal ends 66, 68 to apredetermined position adjacent the distal ends 72, 74. In other words,tangs 62, 64 may be configured to be spaced apart relative to each otherto enable placement of a material restrictor 70.

Insertion of delivery device 60 into the disc space may be accomplishedin any suitable fashion. For example, tangs 62, 64 may be shaped toenable insertion into the disc space. For example, in FIG. 5, tangs 62and 64 are angled together forming a tip which may be initially pushedinto the disc space. The tangs may be separated to form a channel forinsertion of the restrictor. In other embodiments, tangs 62, 64 may beshaped or curved to accommodate insertion. The tangs may be separated asthe restrictor is driven through the tangs into the space.

As shown in FIG. 5, tangs 62, 64 may include projections and otherstructures that are configured to stabilize and position delivery device60 and/or restrictor 70. For example, tangs 62, 64 may include stops 78spaced from distal ends 72, 74 of the tangs. As tangs 62, 64 arepositioned within the disc space, stops 78 may flex or otherwise slideor pass along the opening or channel towards the disc space. Stops 78may be configured to rest against the posterior surfaces of thevertebral bodies adjacent disc space 14 (as shown in FIG. 7) such thatportions 80 and 82 are substantially disposed within the disc space.Regardless of the configuration, stops 78 or other similar structures,may be configured to enable proper positioning of tangs 62, 64 relativethe disc space so as to enable proper positioning of material restrictor70 in the disc space.

In some embodiments, stops 78 may limit anterior migration of tangs 62,64 as delivery device 60 is inserted into disc space 14. Stops 78 alsomay be configured to limit anterior migration of delivery device 60during remaining steps of the method discussed in FIG. 3. In someembodiments, stops 78 may be disposed at a length from distal ends 72,74 ranging from about 20 mm to about 26 mm. However, other positions arepossible and are within the scope of the disclosure. Moreover, there maybe additional stops or structures which cooperate to position tangs 62,64. Moreover, in some embodiments, the end of the tangs or other portionof the tangs may protect the restrictor and/or guide placement of therestrictor. It should be recognized that the distance to which stops 78are spaced from distal ends 72, 74 may be determined by considering suchfactors as the size of vertebral bodies being fused, the size ofmaterial restrictor 70 to be inserted, and the desired position ofmaterial restrictor 70 between the vertebral bodies, such as vertebralbodies 12.

Delivery device 60 also may be configured to retract the neural materialadjacent the disc space 14 to further protect the neural material duringthe procedure. In some embodiments, delivery device 60 may include aretractor component configured to temporarily displace neural material.For example, delivery device 60 may include a medial slightly curvedtang or tangs (not shown) that may function as a nerve root retractor.

With reference to FIG. 5, delivery device 60 may be configured to enablethe insertion of a material restrictor into a collapsed disc space andto reestablish normal disc space height without damaging the endplates.A typical bilateral partial hemilaminotomy used to provide access todisc space 14 may be used to provide an opening that is on average about7 mm wide. Unlike the present system which requires only a smallopening, conventional systems, such as ALIF or PLIF systems may bedifficult to use since such systems require a larger opening then the 7mm of width (or other small region) provided for the AMLIF system. Also,unlike other systems, the present system does not have pedicle screwsagainst which to distract.

Further, unlike some PLIF systems that function by placing a relativelynarrow cage into the disc space in a horizontal position and thenrotating the cage into a vertical position, thus distracting the discspace, the present system does not provide enough space for suchrotation. Specifically, a 12 mm cage placed horizontal into a disc spacerequires an opening at least 12 mm wide, which is substantially morethan the 7 mm space created through the method of the presentdisclosure.

In one embodiment according to the present disclosure, delivery device60 may be configured to distract disc space 76. Delivery device 60 maybe configured with first and second tangs 62, 64, as described above,and disc space 14 may be distracted as material restrictor 70 isinserted through the delivery device into the predetermined position. Ascan be seen in FIG. 5, first and second distal ends 72, 74 may beconfigured to be initially substantially adjacent to one another asdelivery device 60 is inserted into disc space 76 (as indicated by arrow76). Insertion and impaction of material restrictor 70 into deliverydevice 60 may operate to spread first and second distal ends 72, 74apart to accommodate the material restrictor. Impaction of therestrictor down through the delivery device may function to reestablishnormal anatomic disc height and decompress the adjacent neural foramina.

In some embodiments, delivery device 60 may be provided with a coupling(not shown) extending between the first and second tangs 62, 64. Thecoupling may be configured to couple tangs 62, 64 while not interferingwith the insertion of material restrictor 70. In some embodiments,material restrictor 70 may act as a fulcrum as it is inserted throughdelivery device 60 providing a pivot point about which the tangs may berotated to distract the disc space 76 as described above. The couplingmay be configured to assist in the distraction of the disc space byproviding a fixed point about which the elongate tangs can rotate asdistal ends 72, 74 are spread apart and proximal ends 66, 68 are broughttogether. Additionally, the coupling may be configured to allow rotationthrough only a limited range to prevent over-rotation of tangs 62, 64.

It should be appreciated that other types of couplings, or no coupling,may be provided or necessary depending on the configuration of thedelivery device. Moreover, the coupling may be releasable such that therestrictor is able to break through the coupling to a select position.In some embodiments, the coupling may operate to lock or secure therestrictor in a select position.

FIG. 6 provides another schematic illustration of a material restrictor70 being inserted through delivery device 60. As discussed in moredetail below, the material restrictor and the tangs may havecorresponding or mating structure 65, such as a channel and groovesystem, which aids in alignment and positioning of the materialrestrictor during insertion.

FIG. 7 illustrates some of the additional features that may beincorporated into embodiments of delivery device 60. Other features andstructures may be incorporated into delivery device 60 as appropriatefor use in different surgical applications. Exemplary features that maybe incorporated when the delivery device 60 is used for interbody fusionof adjacent vertebral bodies include frangible joints, positioningstructures, and alignment structures.

Exemplary frangible joints 84 intermediate the distal ends and theproximal ends of tangs 62, 64 are shown in FIG. 7 adjacent stops 78.Frangible joints 84 may be configured to couple a restrictor portion 86of each tang to a handle portion 88 of each tang. Restrictor portion 86may be configured to extend into the disc space. In some embodiments,restrictor portion 86 may be adapted to remain within disc space 76,while handle portion 88 may be adapted to be removed from the patient atsome point during the operation. In other words, restrictor portion 86may be removable from handle portion 88.

It should be appreciated that frangible joints 84 may be disposed at anypoint along the length of the tangs 62, 64. As shown in FIG. 7, forexample, frangible joints 84 may be disposed distally from stops 78allowing the stops to be removed as part of handle portion 88. However,other locations for frangible joints 84 are within the scope of thepresent disclosure.

In some embodiments, frangible joints 84 or deliver device 60 may becoated with a sealing material. Any suitable sealing material may beused. The coating may be used to aid in positioning the device,preventing leakage or degradation of the material composing the jointsor delivery device, or any other suitable purpose.

FIG. 7 also illustrates exemplary positioning features or structures 90of delivery device 60. Positioning features 90 may be configured toensure accurate positioning and stabilization of restrictor 70. Anysuitable positioning structures may be provided, including, but notlimited to projections, ridges, teeth, detents, receiving openings,channels, locking buttons, etc.

Positioning features 90 may cooperate with material restrictor 70 toprovide feedback to the user when the material restrictor is disposed inthe desired predetermined position. Further, such positioning featuresmay be configured to aid in retention of the material restrictor in thepredetermined position. A variety of structures may be utilized aspositioning features 90 to provide the feedback and/or retention. Oneexample is shown in FIG. 7 where the delivery device 60 includes atoothed ridge on the inside surface of at least one of the tangs 62. Theridge may be configured to mate with a groove, teeth, etc. disposed onthe exterior surface of the material restrictor 70 (described in moredetail below). Although shown as having corresponding structure on therestrictor, it should be noted that the tangs may include structurewhich does not require any corresponding structure on the restrictor.For example, the tangs may include a raised bump which upon pressure bythe restrictor (regardless of surface structure) is depressed, thusapplying a retainment force against the restrictor.

In other embodiments, positioning features 90 may be provided with agroove on at least one of the tangs configured to mate or correspondwith a ridge disposed on the material restrictor. Other structures andarrangements may be used to secure the restrictor and/or providefeedback to the user. The feedback provided to the user may be audible,visible, or tactile feedback. For example, a click may be heard whenmaterial restrictor 70 reaches a desired predetermined position.Alternatively, the amount of force required to further insert materialrestrictor 70 may increase upon reaching the predetermined position.Other forms of feedback are available and are within the scope of thepresent disclosure.

Additionally and/or alternatively, delivery device 60 may includealignment features, such as channels and grooves, configured tocooperate with material restrictor 70 to guide the material restrictorthrough delivery device 60 during insertion of the material restrictor.A variety of structures may be utilized to retain the materialrestrictor within the delivery device 60. For example, each of the tangs62, 64 may include a lip at the outer side edges (not shown).Alternatively, one or more of the tangs and/or material restrictor maybe provided with longitudinal projections, ridges, grooves, channels,depressions, bumps, etc. configured to aid in alignment of therestrictor. In some embodiments, mating structures may be provided onone or more of the tangs and/or on material restrictor 70.

As discussed above in connection with delivery device 60, the step ofinserting material restrictor 70 into disc space 14 may distract thedisc space. The extent to which the disc space is distracted may bedependent on the dimensions of the material restrictor. It should beunderstood that the dimensions and configuration of material restrictor70 may be selected to reestablish normal anatomic disc space and todecompress the adjacent neural foramina. Other dimensions andconfigurations may be selected according to the practitioner'spreference and patient's needs.

A perspective view of an exemplary embodiment of a material restrictor70 is shown in FIG. 8. In some embodiments, the size of the materialrestrictor may be minimized as the material restrictor may primarily beused as a delivery device for the fusing material into the disc spaceand the adjacent vertebral bodies. For example, in some embodiments, thewidth of the cage may be decreased enabling reduced surgical exposureand nerve root retraction, similar to the exposure used for a simplemicro-lumbar disectomy. This ability to reduce exposure to the discspace may speed patient recovery and reduce required hospital stayswhich occur with the prior fusion methods and systems. Additionally,reducing the amount of exposure may make the procedure easier and morereliable, thus improving the patient's outcome.

The height 94 of the material restrictor 70 may correspond to the normalheight of the disc space in which the material restrictor is to beinserted. For example, the height of material restrictor 70 may rangefrom about 8 mm to about 14 mm to reestablish normal height of the discspace. A practitioner may select a different height (as well as otherdimensions) for the material restrictor based on a patient's needs.

The width 96 of an embodiment of a material restrictor 70 is also shownin FIG. 8. In one embodiment, material restrictor 70 may be about sevenmillimeters in width. Seven millimeters was chosen based oninteroperative measurements made during micro lumbar discectomies. Aseven-millimeter width may allow for insertion through an openingcreated through the small hemilaminotomy with minimal facet jointremoval as described above. However, it should be appreciated that otherwidths may be used without departing from the scope of the presentdisclosure.

Material restrictors 70 of the present disclosure may be of any suitablelength 98. The length 98 of material restrictor 70 may be selected basedon a patient's needs. In some embodiments, material restrictors 70 mayhave standardized lengths that cooperate with stops 78 on delivery tangs62, 64 to place material restrictor 70 in the desired predeterminedposition between vertebral bodies 80. For example, material restrictor70 may have a length of 20 mm, while other restrictors may have a lengthof 26 mm. In even other embodiments, restrictor 70 may have a lengthranging from about 18 mm to about 28 mm. However, other suitable lengthsmay be used as desired by the practitioner without departing from thescope of the present disclosure.

Additionally, in some embodiments, material restrictor 70 may beconfigured with straight or lordotic curves. The curvature of thematerial restrictor 70 may correspond to the curvature of the region ofthe disc in the spine. Further, the tangs may also be suitably curved toaid in placement of the delivery device and/or placement of the materialrestrictor.

As shown in FIG. 8, material restrictor 70 may include a shell 100 thatdefines a central cavity 102. Shell 100 may have a top surface 104 and abottom surface 106 as well as ends 108, 110. In some embodiments, oneend 110 of material restrictor 70 may be substantially closed and theother end 108 may be at least partially open (e.g. opening 152). Centralcavity 102 and the various openings in shell 100 will be described inmore detail below. It should be appreciated that material restrictor 70may be composed of any suitable material. For example, in someembodiments material restrictor 70 may be made of titanium or abiodegradable material.

Material restrictor 70 may include structures which enable the materialrestrictor to controllably travel along delivery device 60. In someembodiments of material restrictor 70, such as the embodiment shown inFIG. 8, at least one of the top and bottom surfaces 104, 106 may includepositioning and/or alignment features, such as channels 122. In someembodiments, the positioning and/or alignment features of the restrictormay correspond with positioning and/or alignment features of deliverydevice 60.

In an exemplary embodiment, material restrictor 70 may include alignmentchannels which correspond with projections provided on tangs 62, 64, orvice versa. For example, material restrictor 70 may include longitudinalchannels 122 configured to cooperate with projections or ridges ondelivery device 60 to form an alignment system. The alignment system mayfunction to prevent material restrictor 70 from slipping sideways out ofdelivery tangs 62, 64, which could cause undesired injuries, such asnerve root injury.

Additionally, material restrictor 70 may be provided with one or moretransverse channels (positioning features) 114 configured to cooperatewith ridges or other like structure of delivery device 60 when thematerial restrictor reaches a select position. These positioningfeatures 112 may provide feedback to the practitioner indicating thatmaterial restrictor 70 has reached the desired position.

The material restrictor may be configured to deliver the fusing materialinto the disc space and the adjacent vertebral bodies. In someembodiments, the material restrictor functions as scaffolding tomaintain vertebral disc space and alignment. Structures may be providedwithin the material restrictor to enhance the scaffolding effect and/orto increase the rigidity of the bridge formed when the fusing materialis introduced.

Material restrictor 70 may include a delivery surface. In someembodiments, the delivery surface may be considered the top and bottomof the material restrictor. The delivery surface may include one or morepreformed openings or delivery holes 116. In alternative embodiments,the delivery surface may include delivery holes 116 that may be formedby drilling through the surface of the restrictor after placement of therestrictor or prior to placement of the restrictor. Delivery holes 116may provide a channel for material to flow from the restrictor into theadjacent bone.

Material restrictor 70 may further include an injection opening 125configured to receive fusing material into cavity 102. The injectionopening may be sized to correspond to a delivery cannula. Alternativelyand/or additionally, the restrictor may include structure enablingattachment of the delivery cannula such that material may be passed intocavity 102. Although shown in FIG. 8, as an oval opening, any suitableopening may be used, for example, in some embodiments, the entire end108 may be open.

FIG. 8 a further provides another schematic illustration of a materialrestrictor. Specifically, material restrictor 70 a is shown with cavity102 a and delivery holes 116 a. As shown, the restrictor may be hollowsuch that fusing material may flow through the restrictor and outthrough delivery holes 116 a.

With continued reference to FIG. 3 and with reference to FIGS. 9 and 10,once the material restrictor is in a select position, delivery channelsinto the cancellous bone may be formed (at 50 in FIG. 3). Such deliverychannels may be drilled from a central cavity of the material restrictorthrough delivery holes 116 (or creating delivery holes 116) into thecancellous bone of each of the adjacent vertebral bodies.

In some embodiments, such as the embodiment depicted in FIG. 9, a drill120, such as an endplate drill or similar device, may be utilized todrill a plurality of channels. Drill 120 may be configured to break thecortical walls of the endplate to create delivery channels 124 that areadapted to allow injected material to spread within the cancellous bone126 of vertebral bodies 12 a, 12 b.

Any suitable device may be used to create the delivery channels. In oneembodiment, a guided locking cannula with an internal flexible drillthat extends at an angle, such as approximately 90 degrees, from thelong axis of the drill may be used. Drill 120 may include an elongateshaft 130 having a longitudinal axis and an insertion end 134 configuredto be inserted into material restrictor 70. Drill 120 may furtherinclude a rotatable tip 136 disposed adjacent insertion end 134 ofelongate shaft 130. Rotatable tip 136 may be configured to extend awayfrom shaft 130 normal to the shaft's longitudinal axis.

It should be appreciated that the restrictor may include an openingconfigured to receive insertion end 134 and rotatable tip 136 of drill120. The drill may be aligned with such openings to ensure formation offlow through channels. Alternatively, a drill may be used to formopenings within the restrictor.

Although a specific drill is disclosed, other channel-making devices maybe used without departing from the scope of the disclosure. Moreover,drilling may occur while the delivery device is maintained in place.However, in other embodiments, the delivery device may be removed bybreaking the handle portion away from the restrictor portion.Alternatively, the tangs may be removed by gently rocking the tangs backand forth. Removal of the tangs and/or removal of a portion of the tangsmay occur at any step of the method as dictated by the procedure and/orpractitioner.

In some embodiments, drilling delivery channels (as indicated at 50 inFIG. 3) may include drilling through a first and a second opposingsurface of the material restrictor, such as a top and a bottom surface.In other embodiments, the material restrictor may be provided withdelivery holes 116, shown in FIG. 8, in one, or both, opposing top andbottom surfaces prior to insertion into the disc space. Additionally,the step of drilling delivery channels into the cancellous bone mayinclude drilling through the cortical bone of each of the adjacentvertebral bodies.

Referring back to FIG. 9, a first delivery channel has been formed witha second delivery channel in the process of formation. In someembodiments, four delivery channels 124 may be drilled, such as shown inFIG. 10. Although four delivery channels are illustrated in FIG. 10, anynumber of channels may be used. For example, in some embodiments, one,two, three, four, five or more channels may be utilized. Moreover, thenumber of channels and the placement of channels may be selected basedon several factors including the desired amount of fusing material to bedelivered, the size of the vertebral bodies to be fused, and theconfiguration of the material restrictor used.

With continued reference to FIG. 3, once the delivery channels areprepared, a fusing material may be delivered to the material restrictorand to the adjacent vertebral bodies via the delivery channels,(indicated at 52 in FIG. 3). The configuration enables deliver of fusingmaterial, such as biological material, via the disc space to bridge intothe cancellous bone above and below the disc space. As the fusingmaterial spreads into the cancellous bone, above and below the discspace, a strong bridge may be produced fusing the vertebral bodiestogether. Due to the structure of the bone, the cortical surface willrestrict the fusing material to the cancellous bone. The porousstructure of the cancellous bone enables the fusing material to spreadand extend into the vertebral bodies, both strengthening the vertebralbodies and creating a solid bridge between the vertebral bodies.

It should be noted that in some embodiments, the material restrictor isnot the device which is being used to support the bridge. Instead, insuch embodiments, the material restrictor simply operates to deliver thefusing material into the disc space and the adjacent vertebral bodiessuch that the fusing material defines the strength of the construct. Inother embodiment, structure within the material restrictor may enhancethe strength of the bridge or construct, such as providing reinforcingstructures within the bridge. For example, reinforcing bars or the like,may be included within (or introduced into) the material restrictor orthe fusing material to increase the strength of the construct.

As shown in FIG. 11, fusing material 140 may be delivered, such as byinjection, through a material delivery cannula 142, or similar device,to material restrictor 70 as indicated by arrow 141 in FIG. 11. Fusingmaterial 140 may then pass through the delivery channels 124 intoadjacent vertebral bodies 12 a, 12 b. Fusing material 140 may dispersethrough the tribecular channels of cancellous bone 126 and bridge acrossmaterial restrictor 70. The fusing material may harden, cementing andsecuring vertebral bodies 12 a and 12 b with the material restrictor tocreate a fused vertebral section.

In some embodiments, interbody delivery device 60 may be used to deliverfusing material 140 and thus, may operate as a material deliverycannula. For example, in some embodiments, delivery device 60 mayinclude at least two sidewalls that couple the first and second tangsalong the length thereof. The sidewalls may be flexible to allow fordistraction of the disc space. The sidewalls and the first and secondtangs may define a lumen through which fusing material 140 may beinserted into material restrictor 70. In other embodiments, a separatematerial delivery cannula 142 may be coupled to material restrictor 70and used to deliver fusing material 140. The delivery cannula may form atight seal with the material restrictor. The delivery cannula may becoupled to the material restrictor using clamps, structural knobs, orother suitable attachment methods.

Material delivery cannula 142 may include an elongate body 144 thatdefines a lumen or cavity 146. The elongate body 144 includes a proximalend 148 and a distal end 150. Distal end 150 may be configured to couplewith material restrictor 70 such that material may be transferred fromthe cannula to the restrictor. Referring to FIG. 8, coupling end ofmaterial restrictor 70 may be at least partially open to allow fusingmaterial 140 to pass into central cavity 102. For example, the couplingend of material restrictor 70 may be provided with an injection opening152 prior to insertion of material restrictor 70. It should beappreciated that injection opening may be of any suitable size and/orshape and may include one or more openings.

In one example, the coupling end may be partially opened by drill 120,discussed above, after material restrictor 70 is inserted into discspace 76. Material delivery cannula 142, thus, may be configured tocouple with material restrictor 70 such that the opening of the materialrestrictor is in communication with lumen 146 of material deliverycannula 142.

Fusing material 140 may be any suitable biomaterial. In someembodiments, the fusing material may be a bioadhesive material. Forexample, the fusing material may be a biocompatible, bioabsorbable,osteoinductive material. In some embodiments, fusing material 140 may bea biological cement. The cement may be configured to harden into a solidafter a short period of time, such as less than about 10 minutes. Forexample, in one embodiment, a biological cement may be used whichinitially flows as it is injected into material restrictor 70 andprepared vertebral bodies 12 a, 12 b. In some embodiments, the flowingbiological cement may be configured to harden within 2-3 minutes. Thehardening of the biological cement may set the construct and achieve asolid fusion.

Various materials or combinations of materials may be used as fusingmaterial 140. Each of the following materials is provided forillustrative purposes and is not intended to limit the scope of thedisclosure. For example, in some embodiments, Simplex or similarmaterial may be used as a rigid stand-alone fixation. As the biologicalcement spreads through the cancellous bone, across the materialrestrictor, into the opposite vertebral body, forming a rigid fixation,the material strength and durability may become the rate-limitingfactor. Another option may be the use of Simplex or similar materialwith allograft and bone morphogenetic protein over the facet joints,thus developing a solid bony fusion.

The fusing material may be a bioadhesive material that provides rapidhardening and substantially immediate fusion of the vertebral bodies. Insome embodiments, the fusing material may have a short curing period,reduced exothermic behavior during polymerization and other mechanicalproperties such that the fusion remains stable over time. One exemplaryfusing material and related properties may include the use of acopolymer of methyl-methacrylate (MMA) and diethyl-amino-ethylmethacrylate (DAEMA) which may provide controlled curing temperature andgood mechanical properties. Inclusion of hydroxyapatite may improvebone-fusing material interaction. Further, a dispersion of polylactide(PLA) may be used to create a segregated phase, with bioresorbableproperties.

In yet another embodiment, a bone substitute material may be injectedthrough the material restrictor that will form a substantially immediaterigid fixation. The bone substitute material may carry BMPs and may beadapted to be reabsorbed and replaced with bone over time. For example,the fusing material may be configured to be biodegraded whileosteoinductive properties simulate bone grown for physiologic fusion ofthe vertebral bodies. In one embodiment, the fusing material may beconfigured to substantially immediately form the stabilized bridge for aperiod of 6 to 12 months as the bone growth occurs.

It should be noted that in some embodiments, other types of deliverystructure may be used to deliver the fusing material into the disc spaceand the adjacent vertebral bodies. For example, in some embodiments,pedicles adjacent to the disc space may be used to introduce fusingmaterial into the disc space and the vertebral bodies.

FIG. 12 illustrates an intervertebral disc space 14 after one embodimentof the augmented micro lumbar interbody fusion method of the presentdisclosure is completed. Material restrictor 70 is positionedintermediate the adjacent vertebral bodies 12 a, 12 b. Fusing material140 fills material restrictor 70 and has spread into cancellous bone 126of each of the adjacent vertebral bodies 12 a, 12 b. Fusing material 140stabilizes vertebral bodies 12 a, 12 b; anchors material restrictor 70in place, and enables for development of a rigid osseous construct inintervertebral disc space 14.

FIGS. 13-20 further illustrate additional embodiments for the abovemethods, systems and apparatus. It should be appreciated that thedescription and illustration of these embodiments are for illustrativepurposes and are not intended to be limiting in any fashion. Forexample, FIG. 13 provides an alternative embodiment of a materialrestrictor 200. Material restrictor 200 is shown as a kidney-shapedcage, however other suitable shapes are considered and are within thescope of this disclosure. In some embodiments, material restrictor 200may include sidewalls 202, 205. The sidewalls may be flexible,expandable walls (indicated at 206) enabling the restrictor to distendinto a trapezoidal shape upon introduction of fusing material. Thus, insome embodiments, restrictor 200 may be expandable. However, in otherembodiments, restrictor 200 may be a static configuration. In one ormore sidewalls, inlet ports or injection opening, 210 may be provided.

Restrictor 200 may further include a top surface 204 and a bottomsurface 208. Top surface 204 and bottom surface 208 may be configured tocontact the endplate of the vertebral bodies and prevent subsidence intothe bodies. In some embodiments, the top and bottom surfaces may be madeof a substantially rigid material.

FIG. 13 a further illustrates a top view of top surface 204. Bottomsurface 208 may be similarly constructed to top surface 204. As shown,top surface 204 may include a plurality of delivery holes, such asfusing material release points or outlet ports 214. These outlet portsmay be subsequently drilled after placement of the restrictor within thedisc space. Surface 204 may further include a seal 212, such as a gasketperimeter seal, to ensure a tight closure between the restrictor and thevertebral bodies.

FIG. 14 further illustrates restrictor 200. As shown in FIG. 14, in someembodiments, restrictor 200 may include one or more distributionchannels 220, 222. The distribution channels may connect from a sidewall with inlet ports 210 to outlet ports 214 disposed in the top andbottom surfaces 204, 208.

FIGS. 14 a and 14 b further illustrate an exemplary distribution channel222. Referring back to FIG. 14, for purposes of understanding FIG. 14, afirst end of a distribution channel is indicated at 223 and a second endof a distribution channel is indicated at 225. FIG. 14 a provides anenlarged view of first end 223 of the distribution channel. As shown,first end 223 includes a compressed drilling spring ending with a drillbit 228. Drill bit 228 may be configured to penetrate the vertebralcortical endplate bone and cavitate or drill into the softer cancellousbone of the vertebral bodies. By drilling into the cancellous bone, alarger receptacle zone may be provided for the fusing material.

FIG. 14 b illustrates an enlarged view of second end 225 of adistribution channel, including compressed drilling spring 224 and aterminating end, with a socket 226. The distribution channel may enableprecise drilling into the inner cortical surface of the vertebralbodies. For example, a device may be linked to socket 226, thuseffecting drill bit 228 to penetrate into the vertebral bodies. In someembodiments, this drilling spring (distribution channel) may beconfigured to remain with the vertebral body such that the distributionchannel operates as a strengthening or reinforcing structure to thefusing material. Further by leaving the distribution channel, it may bepossible to enhance the tensile and shearing force resistance at thecage-endplate interface. In other embodiments, the distribution channel(such as the spring-drill or drilling spring) may be removed orotherwise positioned within the restrictor or the space.

FIG. 15 illustrates an embodiment for a delivery device 250. Deliverydevice 250 may be configured to deliver restrictor 200 into the exposeddisc space. As shown, delivery device 250 may include a handle 252 andan extension portion 254. Terminating at the end of extension portion254 is an insertion end 258 of delivery device 250. Insertion end 258may include rails or tangs 256 for insertion of restrictor 200.

FIG. 15 a further illustrates insertion end 258 of exemplary deliverydevice 250. As illustrated, insertion end 258 may be shaped to aid indirecting and insertion of the restrictor into the disc space. Forexample, tangs 256 may be shaped or curved, such as c-shaped, to aid inplacement of restrictor 200 within the space. As described above, tangs256 may have alignment features to guide restrictor 200 into a desiredlocation.

Delivery device 250 may include a guiding structure, such as a plunger260, adapted to release restrictor 200 into the select position in thedisc space. In some embodiments, plunger 260 may be operable from thehandle of the device.

FIG. 16 further illustrates operation and features of an exemplarydelivery device 250. Specifically, in the exemplary embodiment, deliverydevice includes alignment features which correspond to alignmentfeatures on the restrictor. For example, delivery device 250 may includea plunger 260 with guide tubes 262. These guide tubes 262 may correspondto inlet ports 210 on restrictor 200. Guide tubes 262 may be coupled tosockets 262 of drilling springs 224 and a tube that is connected to theinjection or inlet port 210 used to fill restrictor 200 with the fusingmaterial. Thus, the delivery device may be operatively coupled to thematerial restrictor.

FIG. 16 a further illustrates another end 253 of delivery device 250.Although shown as being on the end of delivery device 250, such featuresmay be provided on any suitable surface or side of deliver device 250.Specifically, as illustrated, one or more connection ports 264, 266 maybe provided which may enable a DREMEL® or other suitable tool to becoupled with delivery device 250 to operate spring drills containedwithin restrictor 200. In some embodiments, these same ports, or likeports, may be coupled to a tube or be configured to receive a tube todeliver fusing material to restrictor 200. A map or other indicatorsurface, such as shown at 265, may also be provided to aid a user inselectively drilling or connecting to structures within restrictor 200.

FIG. 17 a-20 illustrate a method of AMLIF. It should be appreciated thatalthough described with use of restrictor 200, and delivery device 250,other types of restrictors and delivery devices, as described herein maybe used and such illustrations are not intended to be limiting. In FIG.17 a, at Position A, a delivery device 250 is shown having a handle 252and an insertion end 258. An enlarged view of insertion end 258 is shownin Position B. As shown in Position B, a restrictor 200 may bepositioned within tangs 256 of delivery device 250.

Arrow 300 indicates transition of delivery device 250 from position A toPosition B. Specifically, as indicated by arrows 302, 304 (and shown inFIGS. 17 a and 17 b at Position B), plunger 260 may be moved such thatrestrictor 200 is pushed into place by delivery device 250. Althoughshown as being fully removed from the delivery device, such discharge ofthe restrictor is shown for illustrative purposes and it should beappreciated that any suitable configuration may be used for placement ofthe restrictor. For example, in some embodiments, select positions maybe used to position the restrictor, such that release from the deliverydevice is delayed by using intermediary release positions. Further, asdiscussed above, portions of the delivery device may be configured tobreakaway from the delivery device remaining with the restrictor in thespace. Thus, in use, a surgeon may selectively position delivery device250 and position restrictor 200 into a disc space by moving plunger 260.Any suitable method may be used to move plunger 260. For example, insome embodiments, pushing the bottom of the handle or other suitablelever may result in motion of plunger 260.

FIGS. 18 a and 18 b illustrate one exemplary method of fillingrestrictor 200 with fusing material. As shown, fusing material may bestored or disposed in a syringe 270 or other suitable device. Syringe270 may include a body 274 and a user-manipulable portion 272 to controlrelease of the fusing material. Syringe 270 may be positioned such thatthe syringe tip 276 engages one of the connection ports, such as 266, ofdelivery device 250. In some embodiments, a main valve may be providedwhich enables direct release of fusing material into the central cavityof the restrictor. Thus, a user inserts (indicated at 306) fusingmaterial from syringe 270 into delivery device 250 through to restrictor200. FIG. 18 b illustrates the expansion of restrictor 200, such that asfusing material fills restrictor 200 (indicated by arrow 298),restrictor 200 expands outward as indicated by arrows 310, 312.

Prior to or after filling of the restrictor (main cavity) with fusingmaterial, delivery channels may be created into the vertebral bodies.FIG. 19 a shows attachment of a DREMEL® or other drilling device 280 todelivery device 250. Drilling device 280 may include a body 282 and adrill 284. Drill 284 may be configured to operatively engage socket 226of compressed drilling spring 224 within restrictor 200 (see FIGS. 14 aand 14 b). Drill 284 may operatively engage socket 226 through deliverydevice 250, such as through connection port 266. Arrow 314 indicatesinsertion of drilling device 280 onto delivery device 250, while arrow316 indicates rotation of drill 284.

FIG. 19 b illustrates the effect of drilling device 280 on restrictor200. Specifically, drilling device operatively engages against socket226 of compressed drilling spring 224 through inlet port 210. Rotationof socket 226 (indicated at 318) by drill bit 284, results in drillingspring engaging and drilling up through outlet port 214 through thecortical wall and into the cancellous bone of the adjacent vertebralbody (not shown in FIG. 19 b). Similar, drilling may take place witheach distribution channel, such that a delivery channel is formed intothe cancellous bone adjacent the outlet ports. Arrow 320 indicates thedrilling of the cancellous bone by the end of drilling spring 223.

FIG. 20 provides a schematic illustration of the steps to insert fusingmaterial into the cancellous bone of the adjacent vertebral bodies. Itis noted that in some embodiments, the main cavity of the restrictor maybe filled concurrently with, or substantially concurrently withinjecting fusing material into the adjacent vertebral bodies. Asdescribed previous, a syringe 270 with fusing material may be disposedto inject fusing material into restrictor 200. For example, syringe 270may operatively engage delivery device 250, e.g. syringe tip 276 may beselectively disposed in connection port 266 of delivery device 250. Suchengagement is schematically illustrated by arrow 330.

The fusing material may flow from syringe 270 along the drilling pathinto restrictor 200 and out through outlet port 214 and into theprepared delivery channels of the vertebral bodies. Arrow 334 indicatesthe flow of fusing material into the inlet port 210 of the restrictor200. The fusing materials flows through the channels and along thedrilling springs inserted in the vertebral bodies. The material mayspread through the adjacent cancellous bone, as indicated schematicallyat 280. The drilling springs (and related components, such as the drillbit) may be retained in position (extending out from the restrictor) andmay function as reinforcement structure thus increasing the strength ofthe fusion.

As described above, the fusing material may rapidly harden, thus fusingthe vertebral bodies together. Arrow 336 schematically illustrates therestrictor 200 as disposed in the disc space with the fusing materialextending from each of the outlet ports into the vertebral bodiesindicated at 280. Since the fusing material rapidly hardens, thevertebral bodies will be quickly stabilized. Such a procedure may besimple enough and provide a strong enough fusion of the vertebral bodiesfor a patient to be able to be treated using same day surgery,outpatient surgery or minimal hospital stays. Further the recoveryperiod and costs associated with the procedure may be significantlydecreased.

It should be appreciated that the above methods, systems and apparatussubstantially reduce the recovery periods currently required using priorfusion methods. In prior methods, an interbody cage was tightly wedgedinto the disc space. Bone was then packed into the cage with thepotential to grow through the cage walls over time fusing the vertebralbody above and below. Substantial time was required for the bone toharden, thus affecting a patient's recovery time. If the cage were toloosen before bone growth could take place, a pseudoarthrosis ornonunion occurred.

In contrast, the material restrictor and method described herein isconfigured to deliver fusing material which is configured to hardenrapidly, thus substantially immediately forming a stabilized construct.Thus, substantially minimizing the chances of pseudoarthrosis ornonunion. Further, since the material restrictor functions as a deliverydevice for the fusing material, the size of the delivery device may beminimized such that less of the disc space needs to be exposed. Thereduced exposure and substantially immediate formation of the constructimprove recovery periods and reduce hospital stays. For example, it maybe possible to perform the above method on an out-patient basis. Thesimplified technique may further improve the safety levels for thesurgical treatment. By reducing recovery periods, decreasing hospitalstays, and increasing safety levels, costs for the procedures may bereduced and the patient outcome may be improved.

Generally, and as described above, the disclosed methods, systems andapparatus provide for a minimally-invasive procedure for fusing one ormore vertebral bodies together. The narrowness of the materialrestrictor enables the use of small incisions with minimal disruption ofthe spinal anatomy. Due to the minimally invasive nature of theprocedure, hospital stays should be no longer than for a simple microlumbar discectomy. The injected fusing material not only fuses thevertebral bodies together but also further restricts subsidence andmigration of the cage. Patients with osteoporosis and similar conditionsmay also be treated because the cement injection essentially functionsas a vertebroplasty.

The disclosure set forth above encompasses multiple distinct inventionswith independent utility. Although the present disclosure includesspecific embodiments, specific embodiments are not to be considered in alimiting sense, because numerous variations are possible. The subjectmatter of the present disclosure includes all novel and nonobviouscombinations and subcombinations of the various elements, features,functions, and/or properties disclosed herein. The following claimsparticularly point out certain combinations and subcombinations regardedas novel and nonobvious. These claims may refer to “an” element or “afirst” element or the equivalent thereof. Such claims should beunderstood to include incorporation of one or more such elements,neither requiring, nor excluding two or more such elements. Othercombinations and subcombinations of features, functions, elements,and/or properties may be claimed through amendment of the present claimsor through presentation of new claims in this or a related application.Such claims, whether broader, narrower, equal, or different in scope tothe original claims, also are regarded as included within the subjectmatter of the present disclosure.

1. A system for fusing adjacent vertebral bodies, the system comprising:a delivery device including a guide configured to be at least partiallydisposed in a space between the adjacent vertebral bodies; and amaterial restrictor configured to operatively engage the delivery deviceand be funneled through the guide into a select position within thespace for delivery of fusing material into the adjacent vertebralbodies.
 2. The system of claim 1, wherein the guide includes two tangs.3. The system of claim 2, wherein at least one of the tangs includespositioning features to position the restrictor within the space.
 4. Thesystem of claim 2, wherein at last one of the tangs includes alignmentfeatures.
 5. The system of claim 2, wherein the alignment features areone of a groove and a channel.
 6. The system of claim 2, wherein atleast one tang includes a stop to selectively position the deliverydevice in the space.
 7. The system of claim 2, wherein the tangs areconfigured to be spaced apart from each other.
 8. The system of claim 1,wherein the delivery device is further configured to distract the discspace.
 9. The system of claim 1, wherein delivery device includes ahandle portion and a restrictor portion.
 10. The system of claim 1,wherein the material restrictor includes a shell defining a centralcavity.
 11. The system of claim 1, further comprising a materialdelivery cannula configured to be removably coupled to one of thematerial restrictor and the delivery device such that fusing material isdelivered to the material restrictor.
 12. A delivery device configuredto facilitate the insertion of a material restrictor into a disc space,the delivery device comprising: a first elongate tang having a proximalend and a first distal end; a second elongate tang configured tocooperate with the first tang, the second elongate tang having a secondproximal end and a second distal end; wherein the first distal end ofthe first elongate tang and the second distal end of the second elongatetang are configured to be inserted into the disc space; and wherein theelongate tangs are configured to receive and guide a material restrictorto a select position within the disc space, wherein the materialrestrictor is configured to enable fusing material to flow into bodiessurrounding the disc space.
 13. The delivery device of claim 12 furthercomprising a plunger to release the material restrictor in a selectposition.
 14. The delivery device of claim 10, wherein at least one ofthe first and second elongate tangs include a stop disposed intermediatethe proximal end and the distal end, wherein the stop is configured toaid in positioning the delivery device.
 15. The delivery device of claim14, wherein the stop is disposed at a length fro the respective distalend ranging from 20 mm to 26 mm.
 16. The delivery device of claim 12,wherein at least one of the first and second tangs include a handleportion and a restrictor portion, wherein the handle portion isconfigured to be selectively detached from the restrictor portion. 17.The delivery device of claim 12, wherein at least one of the first andsecond elongate tangs includes alignment features configured tocooperate with the material restrictor to guide the material restrictorthrough the delivery device during insertion.
 18. The delivery device ofclaim 13, wherein at least one of the first and second elongate tangsincludes positioning features configured to cooperate with the materialrestrictor to provide feedback to a user when the material restrictor isdisposed in the predetermined position.
 19. The delivery device of claim12, further comprising a channel enabling operative engagement with thematerial restrictor.
 20. The delivery device of claim 12, wherein thedelivery device includes connection ports configured to link an externaldevice with the material restrictor.